Unlocking the Hernand Castle Strongbox is a fun little puzzle in Crimson Desert in which you have to replicate a melody, but if you're not musically inclined, you might struggle somewhat. To access this safe, you'll first need to enter Hernand Castle and you'll also have to get a key to unlock the door to the room that the box is inside.
Finally, you'll need to acquire a mask in order to actually steal what's inside the box when you're done—the same is true for all other strongboxes as well. Once all those steps are done, you're ready to solve the Hernand Castle Strongbox.
